Means for clamping electrical conduits



Nov. 15, 1949 w M 2,487,912

MEANS FOR CLAMPING ELECTRICAL CONDUITS Filed Jan. 15, 1948 Patented Nov. 15, 1949 FOR GLAMPING.ELEETRICAL CONDUHS Rudyard-KiplingWellman, St; Clair Shores, Mfcln,

assignorto Wellward Too-l Gompa'ny; Inc., Detrait; Mich., acorporation of Michigan Application January 15, 1848;. Serial No.2,495;

The invention relates to clamping means, for securing, electrical. conduits. or cables to apertured electric outlet boxes or similar structurea and has forits obj ects: to provide an improved simple and efiicient device for such purpose which may bemanufacturecl' in quantity in the form of metal stampings at'relatively small cost.

A further object of the invention is to provide a clamping device of the character described which is'compose'd ofa minimum number of parts which may be readily'a'ssembled on the electrical conduit adjacent an aperture in the outlet box for the" purpose of securing the cable in rigid and immovable relation to the apertured wall of the box; This is for the purpose of taking up" and absorbing pulling'jstrains" imparted to the cable and preventing such strains from being imposed upon the usuarcurrent outlet binding posts'towhich the cable is secured onthe interior of" the box. The device: may be: disassembled or dismantled with equal" facility when desired and is of such character as to be adapted" for use. with a variety of electrical cable conduits of difierent'sizes; as well as with outlet boxes hav ing cable receiving apertures of varying diameter therein, 7 i g The improved cable clamping device of the instant invention 'is' of such simple and" eflicient structural character as to be capable of being stamped out of sheet m'eta'li with a minimumv number of forming operations; and" essentially comprises two opposed complementaryseparate cableembracing and. clamping members or plates of generally similar cooperating configuration so as to enable the parts to-bereadily interlocked and secured in clamping relation'to' the cable and to'the outlet' box; through the-medium of a single clamping screw engageable with such complementary clamping platemembers.

Numerous other'objects and advantages of the invention will be apparent: as it is better understood f-romzthe following description which; taken connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

Fig. 1 is a view in side elevation of the assembled clamp member and electrical cableor conduit, and illustrating the same in secured position to the apertured side wall of an electric terminal box, such as a switch box, outlet box or the like.

Fig. 2 is a transverse sectional view on line 22 of Fig. 1. v

Fig. 3 is a vertical sectional view on the line 3-4 of Fig. 1.

1 Glaim. (Cl. 285-65) 2. Fig. 4 is a perspective view of the two complement'ary members: or plates constituting the clamp, in separated or disassembled relation;

Referring to the drawings, the interconnecting cooperating-f clamp members comprise two complementary rigid elements or plate members Ill and lit formed of metal or plastic and which may be formedfforf example of sheet metal. stampings. Each element includes an intermediate outwardly curved or convex cable. holdi g portion 1'3, [3d respectively terminating at one end in. angular-v outwardly extending preferably integralflange. portionsor feet I4, [421' disposed in. substantial alignment and extending in opposite directions. when. the parts are assembled. The clamp el'- ment l0. atoneside of its outwardly curved inter mediate. portion l3, i'sprovided with a projecting ear or/lIug [5; preferably of reduced width and'set off from said intermediate portion by aligned ledges; or shoulders i521. The ear l5is preferably provided. with, a substantially central shouldered. aperture [61 for the loose reception. therethrough of a. single suitably headed'and/or slottedsecur ing bolt or. screw I,|T,.with a minimum of clearance or tolerance. The opposite portion of the clamp element. I0) preferably includes a substantially flat, straight. rigid wall. portion 3' inwardly set; off, from the intermediate curved portion [3." by

a. ledge, or shoulder lflagsaid wall." portion 1'8 in.

turn terminating inv anv inwardly offset, aligned. projecting tongue 19' of reduced width so asto leave oppositely disposed: fiat shoulder or ledge;

portions. 2U at the juncture of said wall and tongue- The remaining complementary clamp element. [2. is similarly provided. at one side of' its outwardly curved; convex. intermediate portion.l3a,,

with av flat projecting ear or lug- 2I set off from.

said. intermediate. portion by oppositely extending aligned shoul'derslor ledge'portionsl'la. Said ear ZTILis provided} with a. central preferably internally threaded aperture 22- for the receptiontherein of the threaded inner end. 23 of the single, screw or bolt element IT. The opposite portion of the member I2 preferably comprises a flat substantially straight integral wall portion 24 inwardly set off from the intermediate curved portion l3a by opposed shoulders 24a. Said wall portion 24 in turn terminates in an angularly extending wall part or flange member 25 having an elongated slot or recess 26 therein for the loose reception of the tongue IQ of the described complementary clamping member It].

From the foregoing it will be apparent that the described complementary clamp members l0 and I2 may be readily and conveniently assembled in conjunction with an electric cable or conduit so as to securely anchor the cable to the clamp members and with the latter in rigid immovable relation to the wall A of an electric terminal box or the like B having the usual aperture D to receive therethrough the cable C and the interconnected oppositely extending flange portions I4, I4a of the clamping elements or plate members I0 and I2.

It will be understood that the terminal box B houses and protects any desired electrical outlet or source of current (not shown) to which the wires to of the enclosed end 0 of the cable are communicably connected as by the usual binding posts, and the opposite or exterior end 0 of the cable may lead to any desired switch controlled electrical fixture where the current to be utilized may be energized at the will of the consumer.

In assembling the parts on the switch or outlet box or cable terminal casing B through the aperture D, the tongue element I9 of clamping element II! is loosely inserted into its mating aperture or slot 26 of the remaining element I2.

With said elements disposed in loose engagement with opposite sides of the cable C on the exterior of the box, the angular oppositely extending feet I4, I4a of the thus loosely engaged clamp elements I0 and I2 are fitted or inserted through the box aperture D.

Aperture I6 of the element I0 is then brought into opposed registry with the threaded aperture 22 of element I2 and the holding screw or bolt I! is loosely inserted through the former aperture and its inner threaded end 23 is rotated into holding engagement with the aligned threaded aperture 22 of element I2. Through the medium of a screw driver or the like the member I! is further rotated to draw the opposed aligned ear portions I and 2I closer together until the respective intermediate curved portions I3, I3a thereof fulcrum outwardly upon the cable in tight clamping engagement therewith which is effectively obtained as soon as. the tongue I 9 bears against the slot 26 in tight non-slipping or immovable relation. The aligned cut away shoulder portions I5a, I8a, 2Ia and 24a at the inner sides of the engaged clamping members, are of sufficient width to afford clearance with a minimum of tolerance for the box wallA so as to iinmovably fit in fixed relation between the oppositely projecting integral box engaging flange portions or feet I4, Ida and the adjacent edges of the diametrically opposed wall portions I8, 24 andears I5, 2! of the clamping elements, as best shown in Fig. 1 of the drawings.

From the foregoing it will be apparent that when the parts are engaged as described, any strains imparted to or placed upon the exterior of the cable or conduit C are transmitted thereby through the engaged clamp elements I0 and I2 and box engaging parts thereof, outwardly away from the cable to the wall A of the box, thereby relieving the inner enclosed portion c of the cable 4 from receiving any of such strains which might otherwise tend to loosen or disrupt its connection with the enclosed electrical binding posts or its other means of attachment to the source of electrical current.

As best seen in Fig. 2, the parts I 4, Ida of the clamp members are inclined rearwardly to engage at their outer ends only against the inner surface of the box wall A adjacent the aperture D, thereby forming a slight acute angle, for example 87, with the intermediate portions I3, I3a of-the respective clamp members. By virtue of this construction it will be apparent that when the screw or bolt I1 is threaded inwardly to engage the parts in clamping relation, the clamp members I0 and I2 are locked against the box wall as the intermediate portions I3, I30, tightly clamp the cable C. Therefore neither the cable nor the clamp will turn relative to the outlet box when the locking bolt I1 is screwed home, and such relative rotation is effectually prevented at all times.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

What is claimed is:

Means for clamping an electrical conduit to an outlet box having a conduit receiving aperture therein, comprising a pair of separable complementary plate members each having an intermediate conduit engaging portion terminating at one end in an angular outwardly extending flange for engaging the interior of the box wall adjacent said aperture, an aperture ear portion extending from one side of each of said intermediate portions of said members and a wall extending from the opposite side thereof, corresponding aligned edges of a said ear and wall being spaced inwardly from said flange to engage against the box wall adjacent said aperture, said walls of the respective members having tongue and slot engaging means, and a single threaded fastening member engaging the apertures of said ears to draw said members together to clamp the electric conduit therebetween with their said angular flanges engaging the inner box Wall surface adjacent its said aperture.

RUDYARD KIPLDIG WELLMAN.

REFERENCES CITED The following references are of record in the file of this patent: 

